Category: Battery News

Vast amounts of excess heat are generated by industrial processes and by electric power plants; researchers around the world have spent decades seeking ways to harness some of this wasted energy. Most such efforts have focused on thermoelectric devices, solid-state materials that can produce electricity from a temperature gradient, but the efficiency of such devices is limited by the availability of materials.

Now researchers at MIT and Stanford University have found a new alternative for low-temperature waste-heat conversion into electricity — that is, in cases where temperature differences are less than 100 degrees Celsius.

The new approach, based on a phenomenon called the thermogalvanic effect, is described in a paper published in the journal Nature Communications by postdoc Yuan Yang and professor Gang Chen at MIT, postdoc Seok Woo Lee and professor Yi Cui at Stanford, and three others.

Since the voltage of rechargeable batteries depends on temperature, the new system combines the charging-discharging cycles of these batteries with heating and cooling, so that the discharge voltage is higher than charge voltage. The system can efficiently harness even relatively small temperature differences, such as a 50 C difference.

To begin, the uncharged battery is heated by the waste heat. Then, while at the higher temperature, the battery is charged; once fully charged, it is allowed to cool. Because the charging voltage is lower at high temperatures than at low temperatures, once it has cooled the battery can actually deliver more electricity than what was used to charge it. That extra energy, of course, doesn't just appear from nowhere: It comes from the heat that was added to the system.

The system aims at harvesting heat of less than 100 C, which accounts for a large proportion of potentially harvestable waste heat. In a demonstration with waste heat of 60 C the new system has an estimated efficiency of 5.7 percent.

The basic concept for this approach was initially proposed in the 1950s, Chen says, but "a key advance is using material that was not around at that time" for the battery electrodes, as well as advances in engineering the system.

That earlier work was based on temperatures of 500 C or more, Yang adds; most current heat-recovery systems work best with higher temperature differences.

While the new system has a significant advantage in energy-conversion efficiency, for now it has a much lower power density — the amount of power that can be delivered for a given weight — than thermoelectrics. It also will require further research to assure reliability over a long period of use, and to improve the speed of battery charging and discharging, Chen says. "It will require a lot of work to take the next step," he cautions.

Chen, the Carl Richard Soderberg Professor of Power Engineering and head of MIT's Department of Mechanical Engineering, says there's currently no good technology that can make effective use of the relatively low-temperature differences this system can harness. "This has an efficiency we think is quite attractive," he says. "There is so much of this low-temperature waste heat, if a technology can be created and deployed to use it."

Cui says, "Virtually all power plants and manufacturing processes, like steelmaking and refining, release tremendous amounts of low-grade heat to ambient temperatures. Our new battery technology is designed to take advantage of this temperature gradient at the industrial scale."

Lee adds, "This technology has the additional advantage of using low-cost, abundant materials and manufacturing process that are already widely used in the battery industry."

Scientists have taken a large step toward making a supercapacitor with energy density comparable to a Li-ion battery.

The supercapacitor packs an interconnected network of graphene and carbon nanotubes so tightly that it stores energy comparable to some thin-film lithium batteries—an area where batteries have traditionally held a large advantage.

The product's developers, engineers and scientists at Nanyang Technological University (NTU) in Singapore, Tsinghua University in China, and Case Western Reserve University in the United States, believe the storage capacity by volume (called volumetric energy density) is the highest reported for carbon-based microscale supercapacitors to date: 6.3 microwatt hours per cubic millimeter.

The device also maintains the advantage of charging and releasing energy much faster than a battery. The fiber-structured hybrid materials offer huge accessible surface areas and are highly conductive.

The researchers have developed a way to continuously produce the flexible fiber, enabling them to scale up production for a variety of uses. To date, they've made 50-meter long fibers, and see no limits on length.

They envision the fiber supercapacitor could be woven into clothing to power medical devices for people at home, or communications devices for soldiers in the field. Or, they say, the fiber could be a space-saving power source and serve as "energy-carrying wires" in medical implants.

Liming Dai, a professor of macromolecular science and engineering at Case Western Reserve and a co-author of the paper, explained that most supercapacitors have high power density but low energy density, which means they can charge quickly and give a boost of power, but don't last long. Conversely, batteries have high energy density and low power density, which means they can last a long time, but don't deliver a large amount of energy quickly.

Microelectronics to electric vehicles can benefit from energy storage devices that offer high power and high energy density. That's why researchers are working to develop a device that offers both.

To continue to miniaturize electronics, industry needs tiny energy storage devices with large volumetric energy densities.

By mass, supercapacitors might have comparable energy storage, or energy density, to batteries. But because they require large amounts of accessible surface area to store energy, they have always lagged badly in energy density by volume.

Their approach

To improve the energy density by volume, the researchers designed a hybrid fiber.

A solution containing acid-oxidized single-wall nanotubes, graphene oxide and ethylenediamine, which promotes synthesis and dopes graphene with nitrogen, is pumped through a flexible narrow reinforced tube called a capillary column and heated in an oven for six hours.

Sheets of graphene, one to a few atoms thick, and aligned, single-walled carbon nanotubes self-assemble into an interconnected prorous network that run the length of the fiber. The arrangement provides huge amounts of accessible surface area—396 square meters per gram of hybrid fiber—for the transport and storage of charges.

But the materials are tightly packed in the capillary column and remain so as they're pumped out, resulting in the high volumetric energy density. The process using multiple capillary columns will enable the engineers to make fibers continuously and maintain consistent quality, Chen said.

The findings

The researchers have made fibers as long as 50 meters and found they remain flexible with high capacity of 300 Farad per cubic centimeter. In testing, they found that three pairs of fibers arranged in series tripled the voltage while keeping the charging/discharging time the same.

Three pairs of fibers in parallel tripled the output current and tripled the charging/discharging time, compared to a single fiber operated at the same current density. When they integrate multiple pairs of fibers between two electrodes, the ability to store electricity, called capacitance, increased linearly according to the number of fibers used.

Using a polyvinyl alcohol /phosphoric acid gel as an electrolyte, a solid-state micro-supercapacitor made from a pair of fibers offered a volumetric density of 6.3 microwatt hours per cubic millimeter, which is comparable to that of a 4-volt-500-microampere-hour thin film lithium battery.

The fiber supercapacitor demonstrated ultrahigh energy-density value, while maintaining the high power density and cycle stability. "We have tested the fiber device for 10,000 charge/discharge cycles, and the device retains about 93 percent of its original performance," Yu said, " while conventional rechargeable batteries have a lifetime of less than 1000 cycles."

The team also tested the device for flexible energy storage. The device was subjected to constant mechanical stress and its performance was evaluated. "The fiber supercapacitor continues to work without performance loss, even after bending hundreds of times," Yu said. "Because they remain flexible and structurally consistent over their length, the fibers can also be woven into a crossing pattern into clothing for wearable devices in smart textiles." Chen said.

Such clothing could power biomedical monitoring devices a patient wears at home, providing information to a doctor at a hospital, Dai said. Woven into uniforms, the battery-like supercapacitors could power displays or transistors used for communication. The researchers are now expanding their efforts. They plan to scale up the technology for low-cost, mass production of the fibers aimed at commercializing high-performance micro-supercapacitors.

In addition, "The team is also interested in testing these fibers for multifunctional applications, including batteries, solar cells, biofuel cells, and sensors for flexible and wearable optoelectronic systems," Dai said. "Thus, we have opened up many possibilities and still have a lot to do."

Power Japan Plus has launched a new battery technology – the Ryden dual carbon battery. This unique battery offers energy density comparable to a lithium ion battery, but over a much longer functional lifetime with drastically improved safety and cradle-to-cradle sustainability. The Ryden battery makes use of a completely unique chemistry, with both the anode and the cathode made of carbon.

“Power Japan Plus is a materials engineer for a new class of carbon material that balances economics, performance and sustainability in a world of constrained resources,” said Dou Kani, CEO of Power Japan Plus. “The Ryden dual carbon battery is the energy storage breakthrough needed to bring green technology like electric vehicles to mass market.”

The Ryden battery balances a breadth of consumer demands previously unattainable by single battery chemistry, including performance, cost, reliability, safety and sustainability.

“Current advanced batteries have made great improvement on performance, but have done so by compromising on cost, reliability and safety,” said Dr. Kaname Takeya, CTO of Power Japan Plus. “The Ryden dual carbon battery balances this equation, excelling in each category.”

Path to Market

Power Japan Plus will begin benchmark production of 18650 Ryden cells later this year at the company’s production facility in Okinawa, Japan. This facility will allow the company to meet demand for specialty energy storage markets such as medical devices and satellites. For larger demand industries, such as electric vehicles, Power Japan Plus will operate under a licensing business model, providing technology and expertise to existing battery manufacturers to produce the Ryden battery.

Batteries for hybrids and plug-in vehicles are growing fast, more than tripling over the past three years to reach 1.4 GWh per quarter, according to the Automotive Battery Tracker from Lux Research. Panasonic has emerged as the leader thanks to its partnership with Tesla, capturing 39% of the plug-in vehicle battery market, overtaking NEC (27% market share) and LG Chem (9%) in 2013.

"Even at relatively low volumes -- less than 1% of all cars sold -- plug-in vehicles are driving remarkable energy storage revenues for a few developers, like Panasonic and NEC, that struck the right automotive partnerships," said Cosmin Laslau, Lux Research Analyst and the lead author of the new Lux Research Automotive Battery Tracker.

"To understand this opportunity, we combined a comprehensive data set of vehicle sales with detailed battery specifications for each car and supplier relationships, yielding a flexible tool that uncovers unexpected insights into this fast-changing market," he added.

Lux Research analysts used historical and current vehicle sales, detailed battery specifications for each car, and supplier relationships to create the Automotive Battery Tracker. Among their findings:

A Rice University laboratory has flexible, portable and wearable electronics in its sights with the creation of a thin film for energy storage.

Rice chemist James Tour and his colleagues have developed a flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte to deliver battery-like supercapacitor performance that combines the best qualities of a high-energy battery and a high-powered supercapacitor without the lithium found in commercial batteries today.

The new work by the Rice lab of chemist James Tour is detailed in the Journal of the American Chemical Society.

Their electrochemical capacitor is about a hundredth of an inch thick but can be scaled up for devices either by increasing the size or adding layers, said Rice postdoctoral researcher Yang Yang, co-lead author of the paper with graduate student Gedeng Ruan. They expect that standard manufacturing techniques may allow the battery to be even thinner.

In tests, the students found their square-inch device held 76 percent of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles.

Tour said the team set out to find a material that has the flexible qualities of graphene, carbon nanotubes and conducting polymers while possessing much higher electrical storage capacity typically found in inorganic metal compounds. Inorganic compounds have, until recently, lacked flexibility, he said.

“This is not easy to do, because materials with such high capacity are usually brittle,” he said. “And we’ve had really good, flexible carbon storage systems in the past, but carbon as a material has never hit the theoretical value that can be found in inorganic systems, and nickel fluoride in particular.”

“Compared with a lithium-ion device, the structure is quite simple and safe,” Yang said. “It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.”

To create the battery/supercapacitor, the team deposited a nickel layer on a backing. They etched it to create 5-nanometer pores within the 900-nanometer-thick nickel fluoride layer, giving it high surface area for storage. Once they removed the backing, they sandwiched the electrodes around an electrolyte of potassium hydroxide in polyvinyl alcohol. Testing found no degradation of the pore structure even after 10,000 charge/recharge cycles. The researchers also found no significant degradation to the electrode-electrolyte interface.

“The numbers are exceedingly high in the power that it can deliver, and it’s a very simple method to make high-powered systems,” Tour said, adding that the technique shows promise for the manufacture of other 3-D nanoporous materials. “We’re already talking with companies interested in commercializing this.”

Rice graduate student Changsheng Xiang and postdoctoral researcher Gunuk Wang are co-authors of the paper.

The Peter M. and Ruth L. Nicholas Postdoctoral Fellowship of the Smalley Institute for Nanoscale Science and Technology and the Air Force Office of Scientific Research’s Multidisciplinary University Research Initiative supported the research.

Researchers at the Pacific Northwest National Laboratory (PNNL) added a kind of nanomaterial called a metal-organic framework, to the battery’s cathode to capture problematic polysulfides that usually cause lithium-sulfur batteries to fail after a few charges.

A paper describing the material and its performance was published online April 4 in the American Chemical Society journal Nano Letters.

“Lithium-sulfur batteries have the potential to power tomorrow’s electric vehicles, but they need to last longer after each charge and be able to be repeatedly recharged,” said materials chemist Jie Xiao of the Department of Energy’s Pacific Northwest National Laboratory. “Our metal-organic framework may offer a new way to make that happen.”

Today’s electric vehicles are typically powered by lithium-ion batteries. But the chemistry of lithium-ion batteries limits how much energy they can store. One promising solution is the lithium-sulfur battery, which can hold as much as four times more energy per mass than lithium-ion batteries. This would enable electric vehicles to drive farther on a single charge, as well as help store more renewable energy. The down side of lithium-sulfur batteries, however, is they have a much shorter lifespan because they can’t currently be charged as many times as lithium-ion batteries.

The reason can be found in how batteries work. Most batteries have two electrodes: one is positively charged and called a cathode, while the second is negative and called an anode. Electricity is generated when electrons flow through a wire that connects the two. To control the electrons, positively charged atoms shuffle from one electrode to the other through another path: the electrolyte solution in which the electrodes sit.

The lithium-sulfur battery’s main obstacles are unwanted side reactions that cut the battery’s life short. The undesirable action starts on the battery’s sulfur-containing cathode, which slowly disintegrates and forms molecules called polysulfides that dissolve into the liquid electrolyte. Some of the sulfur—an essential part of the battery’s chemical reactions—never returns to the cathode. As a result, the cathode has less material to keep the reactions going and the battery quickly dies.

Researchers worldwide are trying to improve materials for each battery component to increase the lifespan and mainstream use of lithium-sulfur batteries. For this research, Xiao and her colleagues honed in on the cathode to stop polysulfides from moving through the electrolyte.

Many materials with tiny holes have been examined to physically trap polysulfides inside the cathode. Metal organic frameworks are porous, but the added strength of PNNL’s material is its ability to strongly attract the polysulfide molecules.

The framework’s positively charged nickel center tightly binds the polysulfide molecules to the cathodes. The result is a coordinate covalent bond that, when combined with the framework’s porous structure, causes the polysulfides to stay put.

“The MOF’s highly porous structure is a plus that further holds the polysulfide tight and makes it stay within the cathode,” said PNNL electrochemist Jianming Zheng.

Metal-organic frameworks—also called MOFs—are crystal-like compounds made of metal clusters connected to organic molecules, or linkers. Together, the clusters and linkers assemble into porous 3-D structures. MOFs can contain a number of different elements. PNNL researchers chose the transition metal nickel as the central element for this particular MOF because of its strong ability to interact with sulfur.

During lab tests, a lithium-sulfur battery with PNNL’s MOF cathode maintained 89 percent of its initial power capacity after 100 charge-and discharge cycles. Having shown the effectiveness of their MOF cathode, PNNL researchers now plan to further improve the cathode’s mixture of materials so it can hold more energy. The team also needs to develop a larger prototype and test it for longer periods of time to evaluate the cathode’s performance for real-world, large-scale applications.

PNNL is also using MOFs in energy-efficient adsorption chillers and to develop new catalysts to speed up chemical reactions.

“MOFs are probably best known for capturing gases such as carbon dioxide,” Xiao said. “This study opens up lithium-sulfur batteries as a new and promising field for the nanomaterial.”

This research was funded by the Department of Energy’s Office of Energy Efficiency and Renewable Energy. Researchers analyzed chemical interactions on the MOF cathode with instruments at EMSL, DOE’s Environmental Molecular Sciences Laboratory at PNNL.

Chief executive of LG Chem said that the South Korean company was considering building an electric vehicle battery plant in China, expecting Beijing's efforts to tackle air pollution to drive demand.

Park Jin-soo also said LG Chem, which currently supplies electric-car batteries for General Motors Co's Volt and Renault cars, will double the number of its customers to 20 in the near future.

"We are considering it (the China car battery plant), which should be in line with market demand," Park said at a press briefing on Friday embargoed until Sunday morning.

LG Chem currently has a factory in Nanjing, China producing small batteries for smartphones and other mobile devices, and Park said the firm is looking at not only Nanjing and other sites for the potential car battery factory.

China's Finance Ministry said last month it will extend a programme of subsidies for buyers of electric-powered vehicles after the current subsidy regime, part of efforts to combat pollution in cities, expires in 2015.

The subsidies were designed to help China meet a goal of putting half a million new-energy vehicles, defined as all-electric battery vehicles and heavily electrified "near all-electric" plug-in hybrids, on the road by 2015 and 5 million by 2020.

LG Chem's crosstown rival, Samsung SDI, said in January that it will form a joint venture in China to spend $600 million on building a car battery plant in Xi'an, Shaanxi province, by next year and on other electric car battery-related businesses over the next five years.

BASF, the largest chemical company in the world, is betting customers will flock to electric cars, using its chemical products to create a battery that will enable vehicles to run longer. BASF, with an annual 1.7 billion-euro ($2.3 billion) research budget, has made battery materials one of 10 areas it’s targeting for growth.

“We are committed,” Adrian Steinmetz, head of global business management at BASF’s battery materials unit, said in an interview at the company’s headquarters in Ludwigshafen. “Having this long-term strategy is typical of BASF. It’s the reason why this company has existed for 149 years.”

To become a major supplier for electric cars, BASF needs to challenge the dominance of Asian market leaders Mitsubishi Chemical Holdings Corp., Sumitomo Chemical Co. and LG Chem. Those companies have an advantage in lithium-ion technology, crucial in car batteries and helped by their proximity to the region’s booming electronics, computer and phones industries.

In November 2013, Robert Bosch GmbH and the Japanese companies GS Yuasa International Ltd., based in Kyoto, and Mitsubishi Corporation, based in Tokyo, set up a joint venture. Known as Lithium Energy and Power GmbH & Co. KG, the new company will be headquartered in Stuttgart. It will develop next-generation lithium-ion battery technology. This next generation is needed in order to make the electric vehicle a successful mass product in the next decade. “In setting up this joint venture, we want to achieve nothing less than a giant leap forward in the development of battery technology. Our aim is to make lithium-ion batteries twice as efficient,” says Dr. Volkmar Denner, who, as chairman of the board of management of Robert Bosch GmbH, is responsible for research and development.

For electric vehicles, more efficient batteries will mean greater range. For consumers, the car will also be more affordable, since the rechargeable batteries can be smaller. Robert Bosch GmbH and its partners are confident that electromobilty will become a mass market from 2020 onward. Electromobility is an important step toward making mobility climate-friendly and sustainable.

Bosch holds a 50 percent stake in Lithium Energy and Power GmbH & Co. KG, with GS Yuasa International Ltd. and Mitsubishi Corporation each holding 25 percent. The composition of the board of management reflects these shareholdings. Its members are Dr. Rolf Speicher from Robert Bosch GmbH, Toshio Ohara from GS Yuasa International Ltd., and Yutaka Kashiwagi from Mitsubishi Corporation. They will initially head up a team of some 70 associates in Germany and Japan.

Bosch will support these joint activities with its entire portfolio of components for electromobility. With its competence in the area of battery packs and battery management systems, Bosch specializes in the monitoring and control of cells and complete systems, as well as in integrating them into vehicles. In addition, it will contribute its know-how in production processes and quality management relating to the large-scale series production of complex products.

GS Yuasa will contribute its many years of experience in manufacturing lithium-ion battery cells whose high density makes for a longer range, as well as its expertise in materials systems and electrochemistry. As an established manufacturer of automotive and non-automotive lithium-ion battery cells, GS Yuasa has a strong engineering team and modern production lines with a high level of automation.

Mitsubishi Corporation will contribute its global sales network and experience as an integrated global business enterprise. In addition, Mitsubishi will use its strengths in the establishment of global value-added chains – which include raw materials, semi-finished products, and marketing – to take the joint venture forward.

XG Sciences announced today it has closed on a strategic investment led by Samsung Ventures Investment Corporation.

Philip Rose, XG Sciences CEO, said the investment will be used to fund additional research and development of the company’s advanced materials. The terms of the investment were not disclosed.

“The investment from Samsung is a real honor for XG Sciences,” Rose said “and it represents another significant milestone in our progress toward commercialization of large-scale graphene applications. A number of applications for our advanced graphene and battery materials have been demonstrated in the electronics industry, and a partner like Samsung will help us move these applications to market faster than we could on our own.

We look forward to formalizing our development work with Samsung SDI in a joint development program aimed at next-generation batteries for consumer electronics and other devices. Samsung’s shareholding will reinforce our leading position and help serve all our customers better.”

“Our investment in XG Sciences is consistent with our strategy to work closely with established market leaders.” says Michael Pachos, Senior Investment Manager at Samsung Ventures. “XGS is a technology leader and has built a significant business in the graphene and energy storage spaces. The company has demonstrated both a technical and business vision in driving adoption of graphene across a wide variety of industries and we look forward to contributing to the progress of XG Sciences.”